Merge tag 'v4.0-rc2' into x86/asm, to refresh the tree

Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/head_64.S

@@ -514,8 +514,38 @@ ENTRY(phys_base)
 	/* This must match the first entry in level2_kernel_pgt */
 	.quad   0x0000000000000000
 
+#ifdef CONFIG_KASAN
+#define FILL(VAL, COUNT)				\
+	.rept (COUNT) ;					\
+	.quad	(VAL) ;					\
+	.endr
+
+NEXT_PAGE(kasan_zero_pte)
+	FILL(kasan_zero_page - __START_KERNEL_map + _KERNPG_TABLE, 512)
+NEXT_PAGE(kasan_zero_pmd)
+	FILL(kasan_zero_pte - __START_KERNEL_map + _KERNPG_TABLE, 512)
+NEXT_PAGE(kasan_zero_pud)
+	FILL(kasan_zero_pmd - __START_KERNEL_map + _KERNPG_TABLE, 512)
+
+#undef FILL
+#endif
+
+
 #include "../../x86/xen/xen-head.S"
 	
 	__PAGE_ALIGNED_BSS
 NEXT_PAGE(empty_zero_page)
 	.skip PAGE_SIZE
+
+#ifdef CONFIG_KASAN
+/*
+ * This page used as early shadow. We don't use empty_zero_page
+ * at early stages, stack instrumentation could write some garbage
+ * to this page.
+ * Latter we reuse it as zero shadow for large ranges of memory
+ * that allowed to access, but not instrumented by kasan
+ * (vmalloc/vmemmap ...).
+ */
+NEXT_PAGE(kasan_zero_page)
+	.skip PAGE_SIZE
+#endif